Addiction is a common fear among people taking pain medications.  Addiction is associated with behaviors such as impaired control over drug use, compulsive use, continued use despite harm, and craving.  When pain medications are taken, they rarely cause addiction.  Addiction is not physical dependence it is a psychological condition.

Tolerance is a physical condition.  If you become tolerant to a drug, the same amount of medication has less effect over time because your body has adapted to it.  You may become tolerant to a side effect or to the medication itself and may require higher doses for the medication to be effective. This is a normal physical response.